1. Field
The invention is in the field of machines and methods for padding pipelines, and more particularly to self-propelled padding machines and methods which utilize a single machine which scoops up the spoils, separates out padding material, and deposits such padding material on the pipeline.
2. State of the Art
When a long pipeline is to be laid such as a cross country gas or oil pipeline many miles in length, an excavator or other such device digs an elongate ditch into which the pipeline is to be subsequently laid. The dirt and rocks removed during the digging of the ditch, the spoils material, is typically dumped in a more or less continuous pile adjacent the ditch called the spoils pile. After the pipeline has been placed in the ditch, typically on sand bags or other supports, the pipeline is initially covered with only loose dirt and small rocks separated from the spoils material, called padding, which padding protects the pipeline when the residual material which remains after separating padding therefrom including rocks and other such material which is dumped on top of the pipeline to backfill the remainder of the ditch. This use of padding material is especially important to protect the outer coating applied to many modern pipelines which coating provides corrosion resistance thereto.
There are a number of different types of motorized pipeline padding devices such as for use such as for padding cross country gas and oil supply pipelines. A first type is disclosed in U.S. Pat. Nos. 5,120,433; 5,195,260; 5,363,574; and 5,430,962 all issued to Osadchuk. The pipeline padding machine comprises a tracked vehicle having a pair of vertically extending, ground level front projections which when driven against the spoils pile funnel the spoils material onto an elevator which carries the spoils material over the top and to the rear of the vehicle into a sorter. The sorter separates padding material from other residual material and deposits separated padding material onto a conveyor which laterally transports the padding material into the ditch onto the pipeline. The residual material such as rocks and other debris are deposited onto the ground behind the vehicle. Since the projections are mounted to the front of the vehicle but the padding material is deposited onto the pipeline at the rear of the vehicle, rocks are frequently knocked onto the unpadded portion of the pipeline causing damage thereto. Such padding machine cannot handle rocks of a larger size which can necessitate separating out such large rocks from the spoils pile prior to use thereof or the use of a separate excavator or similar machine to clear such large rocks therefrom when encountered.
A second type of pipeline padding machine which is separate from but attaches to a motorized vehicle is disclosed in U.S. Pat. Nos. 5,097,610; 5,261,171; and 5,479,726 all issued to Bishop. The pipeline padding machine attaches to the shovel of a tracked bulldozer with a pair of front projections which when driven against the spoils pile funnel the spoils material onto a screening belt which allows padding material to fall onto a longitudinally extending conveyor belt thereunder. The conveyor conveys the residual material into the shovel of the bulldozer or onto a separate laterally extending conveyor belt for subsequent backfilling of the ditch. The padding material on the conveyor belt drops padding material onto a laterally extending conveyor belt which drops the padding material onto the pipeline adjacent the rear of the padding machine. This version suffers from the problem of the padding machine of Osadchuk of damaging the pipeline by inadvertently knocking rocks onto the unpadded portion of the pipeline. An alternate version of the padding machine further includes a generally longitudinally forward extending conveyor belt which conveys the padding material from the laterally extending conveyor belt onto the pipeline slightly ahead of the front projections presumably in an effort to solve such problem. Such padding device still suffers from the other problem of the padding machine of Osadchuk of not being able to handle large rocks. A third type of pipeline padding machine is disclosed in U.S. Pat. No. 5,084,991 issued to Cronk, Jr., which mounts to a tracked bulldozer in place of the shovel and which can be moved vertically and tilted as normally done with the shovel replaced thereby. Such padding machine comprises a longitudinally disposed drum in a frame attached to the bulldozer which drum is rotationally powered. The exterior of the drum includes a screen to pass padding material but not larger spoils material and a plurality of paddles to engage the spoils material and propel such spoils material against the screen. A laterally extending conveyor belt extends outwardly from inside the drum to receive padding material and convey such padding material laterally onto the pipeline in the ditch. The conveyor is disposed behind the front portion of the drum and cannot accept medium sized and larger rocks, therefore suffering from the aforementioned disadvantages of the other prior art padding machines.
Other pipeline padding machines include a pipeline padding machine comprising a sorter which attaches to the side of a tractor by means of a frame and which extends over the ditch which is disclosed in U.S. Pat. No. Re. 34,289 issued to McClain et al. The sorter must be loaded by a separate bulldozer, excavator, or other such device. A similar type padding machine for attachment to the side of a tractor is disclosed in U.S. Pat. No. 4,955,756 issued to Klamar. In U.S. Pat. No. 4,616,957 issued to Burrows et al. is a pipeline padding machine which comprises a sorter and conveyor which mounts to a tracked bulldozer in place of the shovel similarly to that of Cronk, Jr. and which can be loaded by a dump truck in front of the padding machine. A motorized pipeline padding machine having a laterally disposed front feed screw, a system of conveyors, and a sorter is disclosed in U.S. Pat. No. 4,912,862 issued to Bishop et al. A longitudinally forwardly extending conveyor deposits padding material onto the pipeline adjacent the feed screw.
There are various types of sorters known in the art for separating suitable padding material such as dirt and small rocks from larger material not suitable for padding pipelines such as larger rocks, clods of dirt, and other such residual material which might damage an unpadded pipeline. Examples of such include wobbler type sorters which have a plurality of spaced, laterally disposed oblong cross-section wobbler members which rotate ninety degrees out of phase with adjacent wobblers to agitate and transport spoils material while allowing suitable padding material to fall therebetween. A second type of sorter is a vibratory type sorter which typically utilizes a vibrating frame having stacked from top to bottom a grizzly having plurality of spaced bars to exclude larger rocks and other material, and one or more screens which pass only spoils material of a predetermined size so as to pass only suitable padding material through the finest thereof.
The invention comprises a self-propelled pipeline padding machine and a method for padding pipelines without damaging the pipeline by the detrimental impact of rocks or other such material. The pipeline padding machine comprises a motorized vehicle, a sorter means attached to an end of the vehicle such as by a frame means, a loading means attached to the vehicle of such configuration to permit scooping up spoils material from the spoils pile on the same side, from the opposite side, or from both sides of the ditch from the padding machine and for dumping the spoils material into the sorter means, and a chute or conveyor means supported by the frame means which receives padding material from the sorter means and which transports the padding material into the ditch to the side and generally ahead of the vehicle such that rocks and other such debris inadvertently knocked into the ditch such as during the scooping of spoils material falls on the portion of the pipeline which has already been padded. The sorter preferably can be positioned vertically, such as by tilting, using an elevating means so as to adjust for the height of the surface of the ground.
The method of the invention for padding pipelines disposed in an elongate ditch with the spoils material removed during the digging thereof being in an elongate, generally continuous spoils pile or a series of spoils piles alongside the ditch, wherein a portion of the pipeline is unpadded and a portion of the pipeline is already covered with padding material. The method comprises the steps of (a) scooping up spoils material from the spoils pile adjacent the padded portion of the pipeline, moving such spoils material to a sorter, and depositing the spoils material into the sorter, (b) separating padding material from the residual material such as rocks and other debris inside the sorter, which is positioned adjacent the padded portion of the pipeline, (c) conveying the separated padding material from the sorter into the ditch on top of the unpadded portion of the pipeline and slightly overlapping the padded portion of the pipeline immediately adjoining the unpadded portion of the pipeline. Such steps are conducted concurrently, sequentially, or in the order required to fit the particular pipeline padding job or application, while moving continuously and/or intermittently alongside the ditch travelling generally parallel to the ditch in a predetermined direction so as to remain adjacent the padded portion of the pipeline such that rocks and/or other such materials which could damage the pipeline which are inadvertently knocked into the ditch during padding thereof primarily land on the padded portion of the pipeline so as to not damage the pipeline and any protective coating thereon.